import java.util.Scanner;
import java.util.stream.IntStream;

public class Main{
	static IntStream REPS(int v){return IntStream.range(0,v);}
	static IntStream REPS(int l,int r){return IntStream.rangeClosed(l,r);}
	static IntStream INS(int n) {return REPS(n).map(i->getInt());}
	static Scanner s=new Scanner(System.in);
	static int getInt(){return Integer.parseInt(s.next());}

	public static void main(String[]$){
		String na=s.next();
		String a=s.next();
		s.next();
		String nb=s.next();
		String b=s.next();
		System.out.println(
				a.equals(b)?-1
						:a.length()>b.length()||a.compareTo(b)>0
						?na:nb);
	}
}